When Katniss wakes up on Prim’s first reaping day, she heads to the woods to hunt with Gale, her best friend and hunting partner. She brings home a feast that will serve as a celebratory dinner after the reaping.
At the reaping, the mayor reads a speech about the history of the Hunger Games. The Hunger Games are meant as a punishment for the districts that once rebelled against the Capitol. As punishment, one girl and one boy are taken from each of the twelve districts every year and forced to fight to the death until there is only one winner left.
To Katniss’s shock, Prim’s name is called despite the odds against it as the female tribute for District 12. Before Prim can mount the stage, however, Katniss rushes out and volunteers in her place. Peeta Mellark is called as the male tribute, and Katniss is upset because she’s indebted to Peeta from years ago. When Katniss’s father died in a mining accident, Peeta for some reason snuck some bread to her, and this generosity prevented her family from starving.
When it’s time to say goodbye to her family, Katniss promises Prim that she will try hard to win the Games and return. Peeta’s father, the mayor’s daughter Madge, and Gale also come to say goodbye. Madge gives Katniss a mockingjay pin to wear in the arena.
Katniss and Peeta take a train to the Capitol, amazed by the luxury of their compartments. They team up to get Haymitch, their drunken mentor, to stay sober enough to give them advice.
When Katniss arrives at the Capitol, she’s surprised by how normal-looking her stylist, Cinna, is, in comparison to the other very “artificial” citizens of the Capitol. He designs a remarkable costume made out of fake flames for Katniss to wear in the opening ceremony.
The day before they enter the arena, Peeta confesses his love for Katniss in a nationally televised interview, and Katniss angrily believes that it’s all part of his strategy to win the Games.
When they enter the arena the next day, Katniss is able to survive in the woods fairly easily, but soon the Gamemakers engineer a number of obstacles to bring the competitors together. First, a wall of fire drives everyone away from the edge of the arena, and then a series of fireballs target Katniss. One catches her on the calf, and she becomes badly burned.
When Katniss is cornered by the Career tributes (tributes from wealthier districts who have trained their whole life to compete in the Games) at the top of a tree, Rue helps her locate a tracker jacker nest, and Katniss sets it loose upon the Careers. However, Katniss also gets stung and begins hallucinating, and she vaguely remembers that Peeta—who had seemed to be allied with the Careers—put himself in danger and ends up saving her life and telling her to run.
Rue and Katniss team up, but their alliance is short-lived, as Rue is soon killed. Katniss weaves a wreath for Rue and sings to Rue in her last moments, and Rue’s district—District 11—sends Katniss a loaf of bread in thanks.
The Gamemakers who run the Game announce that the rules have been changed so that there can be two winners from the same district, likely to ratchet up the tension of the Games for the viewing audience by getting Katniss to go and try to help Peeta, who was injured by Cato when he saved Katniss. And Katniss does immediately set off to find Peeta. After she finds him, badly injured and not far from death, Katniss realizes that Haymitch wants her to play up the romance for the audience, so she does so, while Peeta is happy just to be with her—he doesn’t seem to be acting at all.
The Gamemakers announce that all remaining contestants can get something they badly need at the Cornucopia where the games began. Katniss is nearly killed by the career tribute Clover from District 2, but is saved by Thresh who then lets Katniss go to repay her for the kindness she showed to Rue (he is from Rue’s district). Thresh then runs off with his own package and Cato’s. Katniss returns to Peeta with her package, which turns out to be medicine that soon returns him back to health.
Ultimately, Katniss, Peeta, and Cato are the last remaining tributes, and Katniss and Peeta gather at the lake to wait for Cato. However, all three are attacked by genetically altered wolf-creatures (who are in fact the revivified and modified bodies of the other dead contestants), and there is a final confrontation on top of the golden horn of the Cornucopia in which Katniss shoots Cato in the hand and lets him fall off the Cornucopia where he is mauled by the wolf-creatures. Katniss puts him out of his misery with another arrow shot.
The Gamemakers then announce that they’re revoking their last rule revision and that there can only be one winner. In desperation, Katniss comes up with a plan, giving Peeta and herself each a handful of poison berries that Peeta had accidentally gathered. On the count of three, they start to place the berries in their mouths, committing joint suicide, but the announcer stops them in a panic, announcing that they have both won the Hunger Games.
A few days later, after she and Peeta have recovered from their injuries in the Games, Haymitch informs Katniss that she’s in danger because President Snow is not happy that she outsmarted and defied the Capitol. She must continue to pretend to be madly in love with Peeta—it’s her only defense for her actions. Peeta learns that she’s been pretending, however, and he grows distant, agreeing only to pretend for the cameras as they return to their lives back home.